Saliva sampling for use in genetic testing is becoming increasingly common. This is true because saliva naturally contains some cells, such as buccal cells, for example, and saliva generally is easier to obtain and/or work with than is most other sources of cells, including blood and hair, for example. One drawback to using saliva as a source of genetic material in a genetic application, however, is that not all saliva samples contain a sufficient number of cells to provide the genetic material that is required to complete the application. For example, perhaps about 1-50 μg of DNA can be isolated from 2 ml of saliva that naturally exists in the human mouth. This amount is insufficient for analysis of a genome that involves several thousand separate polymerase chain reactions, an amount of such reactions that is sometimes performed in the analysis of a genome. Further, of the 1-50 μg of DNA obtained, perhaps about 10% is from one or more bacterial species that are normally present in the mouth (such as Streptococcus mutans and certain Lactobacillus species, for example). This contaminating bacterial DNA can lead to failed assays and, worse, to misleading results.
Many devices have been developed for collecting saliva to test for presence of particular antibodies and antigens, such devices are unsuitable for DNA and RNA testing regimes, because these devices do not collect a sufficient amount of recoverable cell and cellular material to be used for large scale testing or field testing. Although it is known that increasing cell concentrations in saliva samples would be useful, and devices are being developed for collecting cell materials by scraping mucous surfaces to collect tissue, Applicant is unaware of a practical method or apparatus which are useful in the field, on a large scale, which can produce and collect saliva fluid samples with enhanced concentrations of cells from the test subject for genetic or other cell-based testing. The distinction is important because, while tissue samples are useful for certain applications and testing scenarios, saliva fluid samples are easier preserve and ship to testing labs from field locations with limited facilities. For example, devices which scrape tissue to accumulate cellular material require a substantially larger volume of buffer fluid, which is relatively expensive to obtain and ship, to preserve the sample retained on the scraping device, and testing requires a step of removing the cell material from the scraper prior to evaluating the sample. Saliva fluid samples, by contrast, merely require the addition of small amount of buffer solution—a few drops for a 2 ml sample of saliva, for example—and do not require the additional step of removal from the scraper.
Additionally, existing devices for collecting fluid samples are awkward to use for both the tester and the subject as they generally require spitting or drooling into a separate collection cup of some sort. This is both annoying (which impacts participation of subjects), unsanitary, and creates the potential for contamination of samples.
In certain circumstances, it is important to filter debris from the collected specimen in order to be able to extract Ribonucleic Acid [RNA] from the sample or simply to remove large particles.
What is needed therefore is a saliva sample collection device that is optimally arranged to increase cell concentration with respect to the cell concentration that is normally present in saliva sample. Further, the needed saliva sample collection device should be user friendly, simple to operate and sanitary for use so that members of the public, as well as healthcare professionals may use the device effectively.